Method of forming inner tubes for tires.



No. $42,217.y PATNNTED, JAN. 29, 1907IA JA. H. MARKS. METHODv OP'FORMING INNEN 'NUBES POR TIRES.

` .ufr'monrol FILED 113.15. 1905.

S. WJINESSES:

" A INVENT/ v BY.

IINITED STATES PATENT OFFICE.

ARTHUR HUDSON MARKS, or AKRON, OHIO.

METHOD OF FOl`\\'M,|"l\J Giv INNER TUBES FOR TIRES.

No. s421217.

.Application filed Tehi-nary 1 To all whom it' 711,04/ concern;

Be it known that I, ARTHUR HUDSON MARKS, a citizen of the United States, residing at Akron, in the county of Summit andv State of Ohio, have invented certain new anduseful Improvements in Methods of Forming Inner Tubes for Tires, of which the following is a specification. l

' This invention relates to an improved method of forming pneumatic tires, and particularly to inner tubes therefor; and the object is to provide an inner tube having vulcanized joints and a dense smooth inner surface.

With the above object in view the 'invention consists in the novel 'features of construction hereinafter fully described, particularly pointed out in the claims, and clearly illustrat'ed by the accompanying drawings, in

Figure 1 is a view showing a layer of rubber upon the mandrel about which it is wrapped g' Fig. 2, a similar' view showin? several layers or plies upon the mandrel; 3, a view illustrating one method of joining the ends of the straight tube 'to form a continuous tube; Fig. 4, a similar view showing another method of unitingr the ends of the tube; Fig. 5, a fragmentary sectional View of the mold, showing the tube therein; Fig. 6, a transverse sectional view of the tube.l

Inner tubes for pneumatic tires as now manufactured are of two classesthe wrapped tube land the 'molded tube. The former is constructed by wrapping around a Straight smooth steel mandrel sheets -of rubbergum, then placing the Whole within a vulcanizer and vulcanizing the same, after which the `ends are brought togetherandrce' mented. The latter is constructed in vthe same manner, except that after the tube is formed onthe mandrel it is removed therefrom and the ends brought together, after which it is placed in a mold' and filled with hot air or steam and then vulcanized While still in the mold. In the iirst method described the tube hasa smooth inner surface, but a cemented joint which is not durable. In the second method the tube has a vulcani ized joint which is durable; but owing to the method of manufacture vits inner surface vis, porous and in hard usage is inclined to split or crack. The present invention is direetedjoV the rovision of an inner tube havinga vulcanv ized joint, but at the same time a smootlr` Adenscinner surface, and it consists in wrap- Specication of Letters Patent,

Patented Jan. 29, 1907.

5,1905. Serial Nox 245.783.

ping about a straight mandrel 1 a ply or layer 2 of rubber' compound so prepared or conipeunded as to vuleanizecomparativelyslowly. The whole is then placed in a vulcanizer and 6o semivulcanized. This semivulcanization of the layer 2 while on the mandrel imparts to it a smooth dense inner surface and gives it sufliient strength and elasticity so that it can be' handled without difficulty in vproceeding 6 with the remaining steps to complete the manufacture of the inner tube. After removing from the vulcanizer and drying the outer surface of layer 2 it is given while still on the mandrel a light coat 3 of vulcanizing 7-o n rubber cement. A second layer or ply of rub# 'ber compound is then applied, and as many layers are. used as may be necessary to'form a tube of the desired thickness, a coating of rubber cement 3 being placed between each 7 5 layer of rubber and Aits predecessor. The. rubbereompound of the second and succeeding layers, if any, i's preferabl such as will vulcanize in the same length o time as is required to complete the vulcanizationof the 3QV semivulcanized inner ply or la rer 2t .The second layer 4 is rolled carefully into goed contact With the irst layer at all pointsh and'ffie tube thus formed by said layers Withdrawn from the-mandrel and its ends', "5 brought together and joined either` bytelog scoping one into the other, as illustrated in Fig, 3, or by bringing them intocontact and joining with a bushing 5 of the same rubbercompound, placed either inside' or outside'oy the tube. The tube inthis condition is then placed in a, moldfand inflated with air ork steam and the mold positioned in the vulcanizer and the tube vulcanized in the usualv Sway, the result being that the close-grained` 95;! inner surface .secured by semivulcanizing the tube while'upon the mandrei is retained in the finished tube, while at the same time Va tube ris providelin which the ends are joined by vulcanizing and not' by cementing.

In order' to secure a smooth dense inner surface, the tube mist be vulcanizedupon a A ,niandreh and to pnovide it with vulcanized j joints it has heretofi rie been necessary to remove it from the' m ndrel before vulcaniza- 105 tion, the latter opeiiationbeing performed entirely after the e ds are joined for vul- IVith my iethodthe inner layer i`s.,y11l f:\.iii7.cd whilehion thev mandrel to a sufficient degree to nhake its inner surface lic .smooth andclose-grained and give it vsuiiji- .,ipntstrengthrand elasticityT to permit of its TOO' Letters Patent of the UnitedStates, is'- being handled during the remainin steps in the manufacture of a completed tu e and at the saine time permit of a further vuleanization to Yulcanize the inner ends and com f plete the tube.

'The tube may be formed of one or more layers, and if one layer is used the same, like layer 2, is formed of a rubber compound thaty will vuleanize slowly, so that it may be partially vulcanized Vupon the mandrel and then removed, its ends approximated, and l the vulcanization completed, as hereinbel'ore described. v

A retaining material, such as cloth, may be placed around the mandrel prior to the wrapf ping ol the lirst layer of the rubber therearound instead of placing the rubber direct lj around the mandrel, as he1ei11l et"ore set Jforth. t

Having thus fully described my invention, what I claim as new, and desireI to secure bj;

l. The improved method of forming inner ltubes for pneumatic tires consisting in plaeingl a slowl),vuleanizing rubber compound about a mandrel, partially vuleamzmg the same wlule on the mandrel, then placing one 0r more layers ol' rubber compound so eomounded as to vuleanize in the time necessaryY i to complete the vuleanization oi' said inner layer upon the latter', then removing the tube thus formed from the mandrel, then ap proximating the ends of the tube, and inally rulcanizing the whole.

2. The improved method of forming inner' 1 tubes for pneumatic tires consistingl in placing a layer of rubber compound about, a In andrel wrapped with a retaining material, such as cloth, partially Vulcanizing the same While on the mandrel, then removing from the mandrel, turning inside out, then approxil mating the ends of the tube, then placing in a. mold, and iinally completing the vul lani?Ak tion. n

3. '.lhe, improved method of forming inner tubes for pneumatic tires consisting in placing a layer ol rubber compound about. a niandrel wrapped with a retaining material, such as cloth, partially Vuleaniziug the same while on the mandrel, then removing from the mandrel, turning inside out, then approximating the ends of the tube, then placing they tube in a nzold, and linallP completing the vuleanization ln testinrouj whereof l allx my signature in presence oie two \\'itnesses,.

Alt'lillilt lllili-SON MARKS. Wit ies-ses:

.l, l.. A\I,\nsn.\i.i, ll, A. Marlins-teit. 

